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Over the last few years there has been a surge of activity within the physics community in the emerging field of Econophysics—the study of economic systems from a physicist's perspective. Physicists tend to take a different view than economists and other social scientists, being interested in such topics as phase transitions and fluctuations. In this dissertation two simple models of stock exchange are developed and simulated numerically. The first is characterized by centralized trading with a market maker. Fluctuations are driven by a stochastic component in the agents' forecasts. As the scale of the fluctuations is varied a critical phase transition is discovered. Unfortunately, this model is unable to generate realistic market dynamics. The second model discards the requirement of centralized trading. In this case the stochastic driving force is Gaussian-distributed "news events" which are public knowledge. Under variation of the control parameter the model exhibits two phase transitions: both a first- and a second-order (critical). The decentralized model is able to capture many of the interesting properties observed in empirical markets such as fat tails in the distribution of returns, a brief memory in the return series, and long-range correlations in volatility. Significantly, these properties only emerge when the parameters are tuned such that the model spans the critical point. This suggests that real markets may operate at or near a critical point, but is unable to explain why this should be. This remains an interesting open question worth further investigation. One of the main points of the thesis is that these empirical phenomena are not present in the stochastic driving force, but emerge endogenously from interactions between agents. Further, they emerge despite the simplicity of the modeled agents; suggesting complex market dynamics do not arise from the complexity of individual investors but simply from interactions between (even simple) investors. Although the emphasis of this thesis is on the extent to which multi-agent models can produce complex dynamics, some attempt is also made to relate this work with empirical data. Firstly, the trading strategy applied by the agents in the second model is demonstrated to be adequate, if not optimal, and to have some surprising consequences. Secondly, the claim put forth by Sornette et al. that large financial crashes may be heralded by accelerating precursory oscillations is also tested. It is shown that there is weak evidence for the existence of log-periodic precursors but the signal is probably too indistinct to allow for reliable predictions. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This dissertation examines the reaction of common stock prices to changes in bond ratings by Moody's Bond Service. The question is whether an announcement of a re-rating by Moody's is new information. There are only two studies of stock price reaction to bond changes and the results are conflicting. Pinches and Singleton (1978) [PS] concluded that any reaction comes well before the re-rating. Griffin and Sanvicente (1982) [GS] found that their portfolio test indicated that rating changes do convey new information. This was particularly true for downgradings. Both studies used monthly data and neither performed a statistical testing of residual reversals. PS provided a graph of the residuals which indicated the presence of a reversal trend. GS provided no information on this topic. This study, using daily data and the cumulative prediction error technique, finds that bond re-ratings offer new information. The results indicate that the market only partially anticipates the bond change. For the downgrades, the excess return on the announcement day is .6% which is statistically significant. The residuals reverse after the announcement day, but are not statistically significant. The upgrades do not have a significant reaction on the announcement day, but have a statistically significant negative reaction from day 1 to 10. The cumulative residual for days 1 to 10 is -2.8% with a test statistic of -3.85. This study finds as PS that there is some anticipation for both upgrades and downgrades. It extends their work by statistically testings the reversals after the announcement date and by testing the announcement day effect. There is significant abnormal return for the downgrades on the announcement day and the upgrades have a significant reversal in their residuals from day 1 to 10. This provides both support and extension of Griffin and Sanvicente's results and suggests that Moody's is offering the market new information.

本文主要探討新股初次上市(櫃)前後期間的股價反應，並藉由觀察準上市(櫃)公司正式上市(櫃)前於興櫃市場交易的股價反應，來驗證興櫃市場的價發現機能。實證結果顯示，上市(櫃)申請日起至興櫃市場最後交易日止期間平均持有報酬47.01%、上市(櫃)首日異常報酬為58.37%、正式掛牌上市(櫃)第二交易日起至一年後的報酬表現，新上櫃股票報酬為14.01%普遍優於新上市的-1.23%。 興櫃市場的價格發現機能相關研究方面，興櫃市場的價格發現機能相關研究的結論為:IPO首日超額報酬在興櫃市場就已經能率先適當反應，興櫃市場是有價格發現機能的，IPO首日超額報酬存在，很有可能是因為承銷價低估。 / This research aims to investigate the performance of IPO stocks during their offering. Our sample consists of IPO announced from March 1, 2005 to February 28, 2010 drawn from the Taiwan Economic Journal. The empirical results show that (1) the return from the day applying to TWSE or OTC to the last trading day on emerging stock market is 47.01%. (2)The IPOs market adjusted return on the first trading day is 58.37%. (3) The performance of IPO stocks listed on OTC is better than stocks listed on TWSE after their offering. We also observed the stock price before listing to test price discovery function of emerging stock market. Our research show that stocks price on emerging stock market has appropriately reacted before listing. Emerging stock market has price discovery mechanism.

Yu Xin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 35-38). / Abstracts in English and Chinese.

by Lee Hing Wah. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (p. 238-247). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest dissertations and theses, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

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Thesis (MBA (Business Management))--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Prior to 30 June 1999 companies in South Africa were not allowed to buy back their own shares. Amendments to the Companies Act, the Companies Amendment Act (Act 37 of 1999) radically changed the philosophy around capital maintenance. The result of this amendment is that a company is allowed to buy back its own shares and finance the backbuying of its shares under certain circumstances. A sample of 140 companies listed on the Johannesburg Securities Exchange for the period 2000 to 2005 was selected. The backbuying of shares by the relevant company, subsidiary and trust was analysed for the period 2000 to 2005. For the purposes of this empirical study, the financial sector, as well as the alternative exchange, that is focussed on good quality small and medium-sized high growth companies, were excluded during sample selection. The outcome of this exploratory study is the identification of the fact that a share buyback took place or not in Tables 4.1 and 4.2; a summary of the number of shares bought back in Table 4.3; and, in Table 4.4, a summary of the number of shares bought back, expressed as a percentage of the weighted average number of shares in issue. / AFRIKAANSE OPSOMMING: Maatskappye in Suid-Afrika was voor 30 Junie 1999 deur die Maatskappywet verbied om hul eie aandele terug te koop. Wysigings aan die Maatskappywet, naamlik die Wysigingswet op Maatskappye (wet 37 van 1999) het ’n radikale verandering bewerkstellig in die filosofie rakende kapitaalinstandhouding. Die gevolg van dié wysigingswetgewing is dat maatskappye sedert 30 Junie 1999 hul eie aandele kan terugkoop en in sekere omstandighede die aankoop van hul eie aandele finansier. ’n Steekproef van 140 genoteerde maatskappye op die Johannesburgse Aandelebeurs is geselekteer vir die tydperk 2000 tot 2005. Die terugkooptransaksies van aandele deur die betrokke maatskappy, filiaal en trust is opgesom vir die tydperk 2000 tot 2005. Hierdie empiriese ondersoek het die finansiële sektor, asook die alternatiewe beurs van die Johannesburgse Aandelebeurs, wat fokus op goeie kwaliteit klein en mediumgrootte maatskappye met groot groeipotensiaal, tydens die steekproefseleksie uitgesluit. Die resultate van hierdie empiriese ondersoek is die identifisering en opsomming van die terugkooptransaksies van aandele vir die steekproef in Tabelle 4.1 en 4.2; ’n opsomming in Tabel 4.3 van die getal aandele teruggekoop; en ’n opsomming in Tabel 4.4 van die getal aandele teruggekoop, uitgedruk as ’n persentasie van die gemiddelde getal uitgereikte aandele.

Abstract There are lots of disadvantages such as the complicated of legal, the inefficiency of decision and the lack of performance. So the government had established ¡§The Privatization Promoting Group for the Executive Yuan of the Republic of China¡¨ in July 1989. The chairman of Council for economic planning and development was the convener. It had made a series of the privatization of stated-owned policy and planned the privatization of stated-owner¡¦s schedule according to different character. Recently stock releasing had already failed. The government, the administration and the employee was dissatisfied with the process of stock releasing. So our study mentioned the design of financial imagination. This design was that led into employee stock ownership plan in the success of the privatization of state-owned and included stock ownership of stock floatation. Both of the close-ended periods were extended to the infinite period. At last our study took an example for Chunghwa Telecom Company and evaluated this design if whether can be executed. My study found that this design could make the employee gain the director number of 1.3 to 2.6. It would enhance efficiently the director number and stabilize the employee ownership. My study expected that it had lots of advantages as follow: (1) Benefit for the privatization of stated-owned (2) Protecting the terms of the employee¡¦s equity (3) Making the employee ownership system (4) Solving the dispute between labor and capital (5) Rational for the stated-wealth¡¦s evaluation (6) Strengthening the corporate governance

published_or_final_version / Statistics / Doctoral / Doctor of Philosophy